1. Field of the Invention
This invention relates to an improvement in a process for hydroconverting coal to liquid hydrocarbon products in the presence of a metal-containing catalyst prepared in situ from a catalyst precursor added to the slurry of coal and diluent.
2. Description of the Prior Art
A coal hydroconversion process is known in which coal, in a hydrogen donor diluent, is liquefied in the presence of a catalyst prepared in situ in the coal-hydrogen donor mixture from catalyst precursors which may be heteropoly acids, such as, for example, phosphomolybdic acid, molybdosilicic acid, etc. See U.S. Pat. No. 4,077,867, column 3, lines 29-30.
The use of heteropoly acids containing a metal constituent of Group VB or VIB as catalysts for liquefying coal in a solvent is known. The catalyst may be employed in solution, for example, in water, alcohols, acetone, ethylacetate, etc. Water is particularly preferred. See U.S. Pat. No. 3,813,329.
A catalytic coal liquefaction process is known in which an emulsion of an aqueous solution of a metal salt in a water immiscible liquid medium is added to the coal slurry. The metal salt is a water soluble salt such as ammonium or alkali metal heptamolybdate. See U.S. Pat. No. 4,136,013.
U.S. Pat. No. 4,155,832 discloses hydrogenation of coal at a temperature below 400.degree. C. in the presence of a transition metal dissolved in an organic solvent. Following the hydrogenation step, the hydrogenated carbonaceous material can be pyrolyzed or catalytically cracked.
It has now been found that in coal liquefaction in which a slurry of coal and a diluent is treated in the presence of hydrogen and a catalyst prepared in situ from a catalyst precursor, the addition of the catalyst precursor in a liquid medium comprising a phenol to the diluent will provide advantages that will become apparent in the ensuing description.
The term "hydroconversion" with reference to coal is used herein to designate a catalytic conversion of coal to liquid hydrocarbons in the presence of hydrogen.
The terms "heteropoly acids" and "isopoly acids" are used herein in accordance with the definitions given in Advanced Inorganic Chemistry, 3rd Edition, by S. A. Cotton and Geoffrey Wilkinson, Interscience Publishers, New York, pages 950-957.
The term "phenols" is used herein to designate compounds in which one or more hydrogen atom in the aromatic nucleus has been replaced by a hydroxyl group as illustrated by phenol (hydroxybenzene); o-cresol (2-hydroxytoluene), m-cresol (3-hydroxytoluene) etc. in accordance with Degering, An Outline of Organic Chemistry, New York, Barnes & Noble, 6th Edition, 1961, pages 189-190.